They will talk about this improbable fightback for a long time in west Cumbria. In front of their biggest home crowd for decades, Whitehaven conceded an early 18-point lead to the all-timers and promotion favourites from Castleford, but surfed an increasingly feverish atmosphere to score five unanswered tries and seal a place in the National League grand final on Sunday week.

"I can't understand the transformation," said a stunned Castleford coach Dave Woods. "We played as we trained for the first 20 minutes, but in the second half there were no excuses, we gave away too much ball."

Castleford had led from the second minute to the 65th, when Haven's nippy wing Craig Calvert squeezed in at the left corner to bring the scores level at 22-all. Then Deon Bird, an experienced Australian loose-forward who really should know better, got himself sin-binned with an idiotic piece of time wasting, and Whitehaven capitalised with two tries from their centre Mick Nanyn to take them within one more win of the promised land of the Super League.

Cas, who were relegated last year, do have a second chance to reach the grand final, playing Halifax at the Jungle next Sunday after their surprise win at Hull KR yesterday. But the scars from this defeat may take a while to heal.

They had looked like a Super League side in the opening quarter, capitalising ruthlessly on Whitehaven's slow start. Brad Davis, the veteran Australian half-back whose British career started with Nottingham City more than a decade ago, was the central figure, setting up the first try for Waine Pryce with a delicate kick and another for Michael Eagar with a slick pass. Bird collected the second from Andy Henderson's kick, and Craig Huby added two conversions and a penalty when Whitehaven's scrum-half Joel Penny was sent to the sin-bin for a professional foul.

But the Cumbrians came back into the game as they settled and the Tigers lost momentum. They cut the deficit to six points with a pair of identikit tries either side of half-time, as Penny twice kicked ahead for Carl Sice to touch down.

Huby nudged Cas four points further ahead with two penalties, but the drama was only just starting, with Craig Chambers stretching over from close range for Havens' third try before Calvert brought them level for the first time.

The mood of euphoria continued as Whitehaven's captain Aaron Lester, a New Zealander who has settled in the area and is one of several of the team who work at the nearby Sellafield nuclear plant, was presented with the club's first-ever trophy in glorious autumn sunshine, a reward for finishing on top of the table. But the real prize will be promotion. They are still 80 minutes away from that, although after yesterday's remarkable events, they must surely go into the grand final, on neutral territory in Widnes, as the favourites.